Crystallography of SiC/MgAl2O4/Al interfaces in a pre-oxidized SiC reinforced SiC/Al composite

A transmission electron microscopy study has been performed on the crystallography of SiC/MgAl2O4/Al interfaces in a pre-oxidized SiC particulate reinforced SiC/Al composite prepared by pressureless infiltration, with a reactant of spine] MgAl2O4 phase at the SiC/Al interface. Four types of different orientation relationships (ORs) were observed between the 6H alpha-SiC and the MgAl2O4 spinet phase, with the SiC(0001) parallel or {0 (1) over bar 12} near parallel to the spinet {111}. Moreover, the cubic 3C beta-SiC and the spinet phase MgAl2O4 exhibited a parallel OR, while the MgAl2O4 and At matrix had a semicoherent interface without a certain OR, except of the near parallel OR for some spine] particles. The observed ORs were analyzed using a geometric method based upon the coincidence of reciprocal lattice points. Possible ORs of other SiC polytypes with the spinet MgAl2O4 phase were also discussed. (c) 2005 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved,